Selective Hydrogenation of Acetylene over Palladium in Ultra High Vacuum
نویسندگان
چکیده
Under ultra-high-vacuum conditions, precoverage of a palladium(ll1) surface with hydrogen does not affect either the kinetics or the extent of acetylene uptake at 175 K. The subsequent reactive behavior of the system is however radically altered. Benzene formation is strongly suppressed, the transformation of adsorbed acetylene to another species (@-phase) is enhanced, and the yield of ethylene is increased. Ultraviolet photoelectron spectroscopy (UPS) observations and coverage measurements suggest that the @ phase consists at least partly of vinylidene, although some ethylidyne may also be present. Experiments with deuterium suggest that vinylidene may be the precursor to ethylene formation; flat-lying acetylene is responsible for benzene production.
منابع مشابه
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